1. Field of the Invention
This invention relates to a composition for molding refractory bricks and more particularly to a composition containing a carbonaceous liquid bonding resin.
2. Description of the Prior Art
In conventional bonded shaped refractory articles, a coal tar pitch is employed as the carbon-bonding percursor. The pitch softens when heated and the softening characteristic is employed to provide the original moldability to the composition in the hot-molding step. When the bricks, however, are installed in a furnace, the pitch constituent softens as a furnace is heated threatening the shape and integrity of the furnace lining. There is, therefore, considerable dependence on the external steel casing of the furnace and internal metallic plating to maintain rigity of the bricks in the furnace.
The use of resins as a constituent of refractory compositions is known. For example in U.S. Pat. No. 3,329,514 there is disclosed a method of making a refractory body that includes refractory materials, graphite and a carbon forming binder. This carbon forming binder is described as tar or pitch which is arranged to hold the mass together when compacted into desired shapes. It is stated in this patent that synthetic resins which carbonize on heating may also be used in whole or in part as the original binder. It is further stated that resins such as furfuryl alcohol resins, phenolic or urea resins may be used to yield between 4 and 7 percent of the porous carbon binder after the composition is calcined at a temperature of 2000.degree. F. or higher. The above patent is principally directed to a refractory body that includes finely divided silicon nitride dispersed throughout the carbon in the refractory composition. It appears that the refractory compositions are compacted and shaped in a mold and subjected to curing temperatures in excess of 2000.degree. F. to permit the silicon to combine with the carbon and form a silicon nitride.
Other patents which disclose the use of resin binders are U.S. Pat. Nos. 4,058,403; 3,342,627; 4,036,798 and 3,969,124.
There is a need for a refractory composition that can provide stability and load resistance when the shaped refractory bodies are subjected to initial elevated temperatures in the furnace.